Stratos LV/LV-T Technical Manual 97

When the Automatic Sensor Gain is activated, the CRT-P samples the sensor-indicated rate. If, during the 24 hour period beginning at midnight, the total time recorded at maximum sensor rate exceeds 90 seconds, the sensor gain setting is reduced by one step. The sensor gain will be increased by one step if for 7 consecutive days; the time recorded at maximum sensor rate is less than 90 seconds each day.

2.14.4 Sensor Threshold

The effects of rate adaptive pacing are limited to sensor signals exceeding the programmable sensor threshold. Sensor signals below this threshold do not affect rate response (Figure 7). The programmable sensor threshold ensures that a stable rate at rest can be achieved by ignoring sensor signals of low amplitude that are not related to exertion.

If the pacing rate at rest is unstable, or tends to stay above the lower rate without activity, the sensor threshold should be increased. The sensor threshold should be reduced if a sufficient rate increase is not observed at a given level of exertion.

Figure 7 Effect of sensor threshold

2.14.5 Rate Increase

The rate increase parameter determines the maximum rate of change in the pacing rate if the sensor signal indicates increasing exertion.

The “rate attack” is set to standard value of 2 ppm/cycle and is programmable (0.5; 1… (1)…6 ppm/cycle).

The programmed rate increase applies only to the sensor-controlled operation and does not affect the rate changes during atrial-controlled ventricular pacing.